Resonant body structure in string instrument

ABSTRACT

The present invention intends to provide a musical instrument that is improved in the acoustic performance, expanded in the capability of sound expressions in musical performance and suitable for kinds of string instruments more than existing solid guitars, solid base guitars and other string instruments. In a string instrument that generates musical sounds based on a vibration of a string stretched over a resonant body, the resonant body is formed on a basis of three-layer structure made of a top plate, a back plate and an intermediate plate interposed between the top plate and back plate, the top plate and back plate each being made of a single panel that is cut so that a woodgrain direction is a plate surface direction, the intermediate plate that is cut so as to come into contact with the top plate and back plate at end grain being laminated with the top plate and back plate at the end grain, and thereby a resonant body structure is constituted.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a multi-layer structure thatconstitutes a resonant body of a string instrument.

2. Description of the Related Art

In a string instrument such as a guitar, plywood has been used as aconstitution material of a resonant body. It can be said that theselection thereof is made to cope with an increase in the cost owing tothe starvation of a wood resource that becomes a raw material and is notbased on the acoustical superiority thereof. In particular in anelectric guitar that has a resonant body called a solid, in a type inwhich an entirety of a resonant body is coated with a coating filmcontaining a pigment, in comparison with a type where a resonant body iscoated with a clear lacquer or the like, woodgrain does not stand out;accordingly, there is a situation in that the plywood can beconveniently used. Furthermore, a structure of a plywood or laminatedtimber is under study. For instance, JP-A No. 08-72025 discloses as awooden plate material and a manufacturing method thereof a configurationin which at least two kinds of wooden chips each having a ground colordifferent from each other are laminated and adhered in an end graindirection and/or in a terminal direction. However, the invention justintends to obtain, while taking advantage of the stately feeling andtexture that wood materials have, a pattern abundant in colors andvariation.

On the other hand, JP-A No. 2004-58416 discloses an invention relatingto a manufacturing method of a wood material for musical instruments anda wood material for musical instruments obtained by the manufacturingmethod. The invention has a configuration that includes; a firstlaminating in which a plurality of wood single panels is coated with orimmersed in a resin, laminated with a fiber direction arranged constant,followed by thermocompression bonding to obtain a laminated body; and asecond laminating in which an obtained laminated body is sliced at aconstant angle to a direction perpendicular to a laminated surface alonga direction of fiber to obtain laminated single panels, obtainedlaminated single panels are coated with or immersed in a resin,laminated with a fiber direction arranged constant followed bythermocompression bonding to obtain a second laminated body; and in thefirst and/or second laminating, the density of the laminated body iscontrolled in the range of 0.8 to 1.4 g/cm³. The density of 0.8 g/cm³ isone of hard and heavy woods such as oaks or the like and the density of1.4 g/cm³ is comparable to that of coal. The invention intends toprovide a wood material for musical instruments, which has the vibrationcharacteristics very similar to natural wood materials for musicalinstruments such as granadilla and rose wood that are used in clarinetsor the like, and to obtain such advantages that the sound quality ofmanufactured musical instruments is excellent, the difference betweenindividual instruments is slight, the lead time is short, the yield isimproved and the degree of freedom in appearance design is large.

Thus, inventions of wood materials for musical instruments, which havebeen proposed so far, can be said that these inventions have beencarried out in view of the preservation of natural wood species, thatis, with an intention of developing alternative materials therefor.Since the object thereof is to provide only alternative materials, it isnot necessarily developed from the relationship with structure/functionthat a musical instrument should have. In this meaning, the foregoinginventions are developments of simple replacement of raw materials orreplacement materials. By contrast, the inventors of the presentinvention have carried out a study and development based on an idea thata wood material for musical instruments, which has a plywood structureor a laminated material structure, should be compatible as far aspossible with the acoustic characteristics of a musical instrument towhich the material is applied, and came to the invention.

-   -   Patent literature 1: JP-A No. 08-72025    -   Patent literature 2: JP-A No. 2004-58416

SUMMARY OF THE INVENTION

The present invention was carried out in view of the above situationsand has an object of improving the acoustic characteristics more thanstring instruments like an existing solid guitar, solid base guitar orthe like and thereby of expanding the capability in the musicalexpression from a viewpoint of performance. Furthermore, another objectof the invention is to provide a resonant body structure that can havethe acoustic performance suitable for kinds of string instruments.

In order to overcome the above-mentioned problems, in the invention, ina string instrument that generates musical sounds based on vibrations ofa string stretched over a resonant body, the resonant body is formed ona basis of a three-layer structure made of a top plate, a back plate andan intermediate plate interposed between the top plate and the backplate, the top and back plates each being made of a single panel that iscut so that a woodgrain direction may be a plate surface direction, theintermediate plate being cut so as to come into contact with the topplate and the back plate at an end grain and laminated with the topplate and the back plate at the end grain (FIG. 1).

A resonant body structure of a string instrument according to theinvention is a unit for generating musical sounds based on vibrations ofa string. The transmission speed of the vibration transmitted to a woodmaterial varies depending on structures of wood tissues. It is knownthat there is a difference of substantially 4:1 between a transmissionspeed in a direction along a woodgrain and that in a directionintersecting with the woodgrain, that is, the vibration transmitted in adirection along a woodgrain is transmitted at a speed faster bysubstantially four times than the vibration transmitted in a directionintersecting with the direction of the woodgrain.

On the other hand, a string vibration is transmitted from a top surfaceof a resonant body to a back surface thereof. That is, in the beginning,when a string is picked a vibration owing to the string is transmittedthrough a bridge and a pickup to a top surface of the resonant body andfurther through an intermediate portion of the resonant body to a backsurface. Thereafter, the vibration reached the back surface is reflectedand once more goes through the intermediate portion to reach the topsurface. These are repeated. From these, since a material structure isuniform in an existing resonant body, it is considered that thetransmission speed of the vibrations transmitted between the top surfaceand back surface is solely determined by quality of material.

In this connection, in the invention, a resonant body structure 10 isformed on a three-layer structure basis made of a top plate 11, a backplate 12 and an intermediate plate 13 interposed between the top plate11 and the back plate 12. The top and back plates each are cut so that awoodgrain direction may be a plate surface direction, and between thesean intermediate plate that is cut so that an end grain may come intocontact with the top plate and the back plate is sandwiched (FIGS. 2 and3). The top plate and the back plate each are made of a single panel.The single panel means not to be a plywood; however, there is no problemto be a laminated wood. Laminating thin wood sheets with an adhesivemakes plywood, and woodgrain directions of sheets of adjacent layers areintersected at a right angle to each other. Laminating at least two woodmaterials with an adhesive makes a laminated wood material, andwoodgrain directions of all wood materials are substantially inparallel.

The top plate and the back plate constituting a resonant body can bedealt with in three ways of a case where woodgrain directions are incoincidence, a case where woodgrain directions are perpendicular to eachother or a case where woodgrain directions are different from both.Furthermore, the top plate and the back plate can be dealt with in threeways of a case where woodgrain directions are directed in a longitudinaldirection (or a longitudinal direction of a neck) of the resonant body,a case where woodgrain directions are perpendicular to the longitudinaldirection or a case where woodgrain directions are different from both.One in an example shown in FIGS. 2 and 3 corresponds to a resonant bodystructure in which woodgrain directions of the top and back plates arecoincident. In the resonant body structure according to the invention,as each of the top plate and back plate that are formed of a singleplate, a laminated wood can be used, and in the intermediate plate millends called chips or end grain material, which come into contact withthe top plate and the back plate at the grain end and have beenfrequently discarded can be used. Accordingly, the invention contributesas well to the effective utilization of wood resources.

FIG. 1 shows names of various portions of wood sections and cuttings ofwood. In many cases, wood is cut so that a woodgrain direction describedas flat grain or straight grain may appear on a material surface.Accordingly, useless mill ends that are not used as timber aregenerated. In the invention, the mill ends can be used as theintermediate plate. In the invention, the resonant body is formed on athree-layer structure basis including the top plate, the back plate andthe intermediate plate. However, since by superposing two pairs ofthree-layer structures with a back plate or top plate sharing a resonantbody having a five-layer structure can be formed, a structure havingthree layers or more can be taken.

Since the invention is constituted and operates as mentioned above, avibration input transmitted based on the vibration of the string isacoustically processed by a resonant body structure formed on athree-layer structure basis including the top plate, the back plate andthe intermediate plate sandwiched therebetween. Accordingly, advantagessuch that 1) a leading-edge of sound, that is the response thereof,becomes excellent, 2) the sound is not confined but clearly comes out ona surface, that is, excellent in so-called forward-expansion, 3) theecho becomes longer (sustainment becomes longer), and 4) a dynamic rangeis expanded, the acoustic performance is improved and the capability ofmusical expressions can be expanded can be obtained. Accordingly, whenthe invention is applied to a string instrument such as a solid guitar,the acoustic performance suitable for these can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an explanatory view describing names and cuttings of variousportions of sections for explaining a wood material that is used in aresonant body structure according to the invention.

FIG. 2 is an exploded perspective view showing an example of a woodstructure constituting the resonant body structure according to theinvention.

FIG. 3 is a perspective view showing an example of a resonant bodystructure similarly according to the invention.

FIG. 4 is a perspective view showing an example of a resonant bodystructure for a solid guitar similarly according to the invention.

FIG. 5 is a perspective view showing an example of a resonant bodystructure for a solid base guitar similarly according to the invention.

FIG. 6 is a perspective view showing an example of a resonant bodystructure for a solid archtop guitar similarly according to theinvention.

FIG. 7 is a perspective view showing an example of a resonant bodystructure for a solid guitar similarly according to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In what follows, the present invention will be detailed with referenceto embodiments shown in the drawings. FIG. 4 is an exemplification of aresonant body structure 20 of a solid guitar. The resonant body has atop plate 21, a back plate 22 and an intermediate plate 23 interposedtherebetween, the top plate 21 and back plate 22 each being made of asingle plate (the “single plate” as used in this invention includesthose made of a solid board, a laminated board, a particle board and thelike), with woodgrain directions thereof arranged in the same direction,end grains of the intermediate plate 23 being brought into contact withthe top plate 21 and back plate 22 and adhered thereto with an adhesive,the grain directions of the top plate 21 and back plate 22 beingdirected in a length direction of the resonant body. In constituentmaterials of the resonant body structure 20, the top plate 21 is thickerthan the back plate 22, and the intermediate plate 23 is further thickerthan the top plate 21. On a top plate side of the resonant bodystructure 20, several recesses 24 that penetrate the top plate 21 andintermediate plate 23 and end at the back plate 22 are formed forattaching bridges and pickups.

FIG. 5 shows an example of a resonant body structure 30 of a solid baseguitar. In the solid base guitar, a top plate 31, a back plate 32 and anintermediate plate 33 are, similarly to an example shown in the FIG. 4,cut and adhered into one body to form a three-layer structure.Furthermore, on a top plate side a plurality of recesses 34 is disposedwith the same purpose. FIG. 6 shows an example of a resonant bodystructure 40 of an archtop guitar. In the archtop guitar, a top plate41, a back plate 42 and an intermediate plate 43 that are cut similarlyto the above are adhered into one body to form a three-layer structure.In examples shown in FIGS. 5 and 6, thicknesses and directions ofwoodgrain of the top plates 31 and 41, back plates 32 and 42 andintermediate plates 33 and 43 are same as the case shown in FIG. 4.

The resonant body structures 20, 30 and 40 having a three-layerstructure shown in each of FIGS. 3, 4 and 5 are considered that portionsof the intermediate plates 23, 33 and 43 made of the end grain materialexhibit a resonant effect similar to a hollow portion in an acousticguitar. Furthermore, in the resonant body structures 20, 30 and 40, neckattachment grooves 25, 35 and 45, in examples shown in FIGS. 4 and 5,are formed to a depth in the middle of the intermediate plates 23 and33, and in an example shown in FIG. 6, are formed to a depth near theback plate. The attachment grooves 25, 35 and 45 each are one oftransmission ports that transmit a vibration of a string to bridges,pickups and also to the resonant body structures 20, 30 and 40.

FIG. 7 shows an example of a resonant body structure 50 in which twopairs of three-layer structures having a top plate 51, a back plate 52and an intermediate plate 53 are stacked sharing the plate 52 that is aback plate, and thereby a five-layer structure is formed. In theexample, recesses 54 for bridges or the like are stopped at a depth upto an upper intermediate plate 53, and separately therefrom a hollow 56for attaching an electronic component is disposed so as to end at alower top plate 51. A reference numeral 55 denotes a neck attachmentgroove.

In what follows, Examples 1 through 7 in which kinds of wood materialsand thicknesses of plates are varied from each other will be described.Regarding the wood material, alder and basswood are used for the topplate and back plate, and alder, basswood and matoa are used for theintermediate plate. Tests are carried out to evaluate an influence ofthe density on the tone quality. The density is largest in matoa,followed by alder, and further followed by basswood. Examples 1 through7 and evaluation results thereof are summarized in a separate table.

EXAMPLE 1

A plate thickness of a top plate is set at 11.5 mm, that of a back plateis set at 7 mm, and that of an intermediate plate is set at 26.5 mm,alder having the medium density was used for the top plate and backplate and basswood having small density was used for the intermediateplate. These were adhered under pressure by use of a wood adhesive intoan integrated resonant body structure having a three-layer structureshown in FIG. 4. This was formed, painted and necessary components wereattached thereto, and thereby a solid guitar having a thickness of 45 mmwas prepared.

EXAMPLE 2

Thicknesses of a top plate, a back plate and an intermediate plate wereset same as that of Example 1, on the other hand, regarding the woodmaterial basswood of small density was used for all plates, andaccording to a manner same as Example 1 a solid guitar shown in FIG. 4was prepared.

EXAMPLE 3

Thicknesses of a top plate, a back plate and an intermediate plate wereset same as that of Example 1, on the other hand, regarding woodmaterial alder of medium density was used for all plates, and accordingto a manner same as Example 1 a solid guitar shown in FIG. 4 wasprepared.

EXAMPLE 4

Thicknesses of a top plate and a back plate were set same at 11.5 mm,that of an intermediate plate was set at 22 mm, regarding wood materialalder was used for the top plate and back plate and matoa of largedensity was used for the intermediate plate, and according to a mannersame as Example 1 a solid guitar having a thickness of 45 mm shown inFIG. 4 was prepared.

EXAMPLE 5

Thicknesses of a top plate and a back plate, respectively, were set at11.5 mm and 7 mm same as that of Example 3, that of an intermediateplate was set at 23.5 mm substantially 10 and several percent less thanthat of Example 3, regarding wood material alder same as Example 3 wasused, and according to a manner similar to Example 1 a solid base guitarshown in FIG. 5 and having a thickness of 42 mm was prepared.

EXAMPLE 6

By use of a top plate having a thickness of 11.5 mm, a top sideintermediate plate having a thickness of 10.5 mm, a center back platehaving a thickness of 5.5 mm, a back side intermediate plate having athickness of 10.5 mm, and a back plate having a thickness of 7.0 mm andalder for all plates, a solid guitar having a five-layered structuresame as FIG. 7 and a thickness of 45 mm was prepared.

EXAMPLE 7

By use of a top side intermediate plate having a thickness of 9.5 mm, aback side intermediate plate having a thickness of 9.5 mm, and a centerback plate having a thickness of 4.5 mm, all reduced by 1 mm from thatin Example 6, and other plates having thicknesses same as Example 6, andalder for all plates, a solid guitar having a five-layer structure sameas FIG. 7 and a thickness of 42 mm was prepared.

<Evaluation>

It was confirmed that Examples 1 and 2 where basswood low in the densitywas used for the intermediate plate were, in comparison with an existingsolid guitar, remarkably improved in four points of the build-up ofsound, sustainment, clearness of sound and the dynamic range. In Example3 where denser alder material is used, the above four points are furtherimproved more than Examples 1 and 2, and Example 4 where the densestmatoa material is used results in the best result among all examples. Asolid base guitar according to Example 4, which has a three-layerstructure, is excellent as well. Furthermore, Examples 6 and 7 having afive-layer structure are obviously improved in comparison with existingsolid guitar and solid base guitar; however, other three-layerstructures are higher in the performance. When Examples 1 through 5 areevaluated in five grades wherein the acoustic performance of one havingthe best quality is assigned to 5 and one having high quality amongexisting solid guitars is assigned to 3, all are evaluated 4 or more.From these, it can be said that when wood material large in the densityis used as an intermediate material, the acoustic performance can belargely improved. TABLE Intermediate Example Evaluation Top plate plateBack plate 1 Guitar 4 Alder Basswood Alder 45 mm 11.5 26.5  7 2 4Basswood Basswood Basswood 11.5 26.5  7 3 4+ Alder Alder Alder 11.5 26.5 7 4 5 Alder Matoa Alder 11.5 22 11.5 5 Base 4+ Alder Alder Alder 42 mm11.5 23.5  7 6 Guitar 4− Alder Alder Center back Intermediate Back plate45 mm plate Alder plate Alder Alder 11.5 10.5  5.5 10.5 7 7 Base 4−Alder Alder Alder Alder Alder 42 mm 11.5  9.5  4.5  9.5 7DensityBasswood 0.41Alder 0.43Matoa 0.61

What are described in the above table are examples and performanceevaluations when basswood, alder and matoa are used. Kinds of woodmaterials that can be used can further include maple, ash, mahogany orthe like. Among these, examples that use ash exhibited extremelyexcellent acoustic performances. However, since experimental results areslight, examples that use the ash are not included as examples. However,wood materials such as the maple are considered useful as anintermediate material from the density. Other than these, many woodmaterials for musical instruments including walnut, rose wood or thelike can be used. Since string instruments such as the solid guitars aresubstantially constant in shape and dimension and, from an externaldimension of a resonant body thereof, optimum dimensions of therespective plate thicknesses of the top plate, back plate andintermediate plate can be determined. Numerical values shown in theseparate table can be used also for this purpose. According to thenumerical values, the minimum thickness of the top plate issubstantially 7 mm and that of the back plate is similarly substantially7 mm, in the case of the thickness being less than the value, in the topplate, when parts are attached, the strength in the screw mountingbecomes deficient, and both the top plate and back plate becomedifficult to inhibit from cracking or warping. Furthermore, it isalready explained that in order to obtain desired acoustic performancesthe material quality of the intermediate plate, in particular, the largedensity thereof is important; however, in the case of the three-layerstructure, the intermediate plate preferably has a thickness more thansubstantially one third a total thickness. When the plate thickness ofthe intermediate plate is deficient, the acoustic advantages accordingto the invention may be insufficient.

1. A resonant body structure comprising, in a string instrument thatgenerates a musical sound based on a vibration of a string stretchedover a resonant body, a resonant body formed on a basis of a three-layerstructure made of a top plate, a back plate and an intermediate plateinterposed between the top plate and the back plate, wherein the topplate and the back plate each are made of a single plate cut so that awoodgrain direction is in a plate surface direction, and theintermediate plate is cut so as to come into contact with the top plateand the back plate at an end grain and laminated to the top plate andthe back plate at the end grain.
 2. The resonant body structureaccording to claim 1, wherein in the resonant body, woodgrain directionsof the top plate and the back plate coincide with each other and aredirected in a longitudinal direction of the resonant body.
 3. Theresonant body structure according to claim 1, wherein two pairs ofthree-layer structures each of which is made of the top plate, the backplate and the intermediate plate are laminated with the top plate or theback plate shared and thereby form a five-layer structure.
 4. Theresonant body structure according to claim 1, wherein in the three-layerstructure the intermediate plate has a thickness substantially one thirdor more a total thickness.